WASHINGTON  Despite enormous changes since his presidency, the United States still reflects JFK's America.

Fifty years after the election that sent John Kennedy to the White House, the impact of his thousand days in the Oval Office continues to be seen in positive repercussions from the civil rights movement and problematic ones from the Vietnam War. He pioneered the media age that has shaped national politics ever since and expanded the role of the federal government in ways that continue to reverberate.

The generation Kennedy inspired to enter public service is entering retirement age. More than half of those living in the U.S. hadn't been born by the 1960 election, when he claimed a presidency that would be cut short by assassination.

Even so, a third of Americans in a new USA TODAY/Gallup Poll rate JFK as a great president; three-fourths rank him above average. A survey of 65 historians by C-SPAN last year ranked Kennedy sixth in presidential leadership, just ahead of Thomas Jefferson and the only one of the top 10 who didn't serve for more than one term.

When President Obama chose five quotations to ring his Oval Office rug, unveiled in September, he included one from Kennedy in 1963: "No problem of human destiny is beyond human beings."

To be sure, there have been seismic changes in the country since then. The U.S. population has swelled from just under 180 million to more than 310 million. The nation is much more diverse, and the status and role of blacks and women have been transformed. An economy once based on manufacturing is driven by technology. The superpower conflict between the United States and the Soviet Union has been replaced by more complicated global struggles over resources and ideology.

Yet Kennedy's name continues to resonate.

"It's interesting that 50 years later, he still has such a hold and his presidency has such a hold on the American people," says Dan Fenn, 87, a special assistant to Kennedy at the White House who later became director of the John F. Kennedy Presidential Library & Museum. "There are people who say, 'Yeah, but he didn't really do much.' OK, without getting into that cat fight, why is it then?"

Historians and others say Kennedy's legacy endures in part because he governed during an era of tumultuous generational change.

"We were coming to the end of the World War II aftermath, and ... civil rights could not be ignored any more, especially because of Dr. (Martin Luther) King's rise," recalls Sander Vanocur, 82, who covered the Kennedy White House for NBC. "It wasn't as if he brought these around, as the events brought him along — and he fit the role that the new age was demanding."

Kennedy was a handsome young president with a quick wit and an elegant wife, the perfect pair for a new television age. He handled the most perilous moment of the Cold War, averting a nuclear showdown in the Cuban missile crisis. He pursued an expansive domestic agenda that reflected Democratic priorities pent up during Dwight Eisenhower's presidency. He sought global engagement, established the Peace Corps and invigorated the U.S. space program with a mission to go to the moon and back within a decade.

"Something called the modern presidency began around then," says Ted Widmer, a presidential historian at Brown who worked in the Clinton White House. "It is a time of never-ending fascination for Americans, even for those who have the dimmest memories of what Kennedy's actual achievements were."

He notes the success of AMC's 1960s-era Mad Men TV series, crediting its appeal in part to "the excitement of the change that happened" during that time.

Kathleen Kennedy Townsend, Robert Kennedy's daughter and a former lieutenant governor of Maryland, thought of one element of her uncle's legacy the other day. She was in downtown Washington visiting the Newseum, a museum devoted to the news media, and saw from the building's balcony the stretch of Pennsylvania Avenue between the Capitol and the White House.

"When President Kennedy in the Inaugural Parade looked at the pawn shops and the debris on Pennsylvania Avenue, he said, 'This has to be cleaned up,' " Townsend says. The restoration project the Kennedys launched helped lead to today's stylish boulevard lined by the modernistic Canadian Embassy, the refurbished Willard Hotel, pricey restaurants and more.

In a look at Kennedy's legacy, here are three areas in which his influence is felt in the nation today.

'Great hope' on civil rights

Georgia Rep. John Lewis says he owes his life to JFK.

Lewis was among the Freedom Riders who had gathered at the First Baptist Church in Montgomery, Ala., to hear King speak on May 21, 1961. A white mob surrounded the church. U.S. marshals, dispatched by Attorney General Robert Kennedy, used tear gas to repel their repeated assaults.

"Many of us probably would have been killed that night" without President Kennedy's decision to intervene, says Lewis, 70, a 12-term Democratic congressman. "Not only his election but his candidacy ushered in a period of great hope, a great sense of optimism, and by the time he was elected and became president, it was a period of great expectation."

Kennedy raised those expectations during the 1960 campaign.

King had been arrested during a demonstration in Atlanta and sentenced to hard labor in a rural Georgia prison on a trumped-up traffic charge, raising fears among supporters for his life. Despite concerns about riling white Southern voters, Kennedy called Coretta Scott King to express support for her husband. Robert Kennedy contacted the judge involved and won King's release.

As president, Kennedy didn't always fulfill the expectations of civil rights leaders. He discouraged them from holding the 1963 March on Washington, arguing that any violence would imperil passage of the Civil Rights Act then before Congress. The bill he had introduced outlawed discrimination in voter registration and public accommodations, but advocates complained that it had been watered down, without provisions on employment and police brutality.

Even so, Kennedy moved further on civil rights than his predecessors. In a radio and TV address to the nation in June 1963 — a century after Abraham Lincoln had signed the Emancipation Proclamation— Kennedy became the first president to call on all Americans to embrace civil rights as a moral imperative. The year after JFK's assassination, President Johnson pushed the landmark Civil Rights Act through a bitterly divided Congress by invoking the slain president's memory.

"Taking 100 years from the Emancipation Proclamation to take strong action remains a scandal in our history," says Harris Wofford, 84. He had been an aide to Kennedy on civil rights and was later a U.S. senator from Pennsylvania. "But it was a great struggle and a great achievement. Kennedy was a part of that; Johnson was a part of it, and so was King."

"If he had not been president, I think things would be different today," Lewis says of JFK.

There have been political consequences as well.

When Johnson signed the Civil Rights Act of 1964, he told aide Bill Moyers that Democrats would face a backlash from the white Southerners who had been part of the Democratic coalition Franklin Roosevelt forged. "We have lost the South for a generation," he warned.

Today, African Americans are the most loyal supporters of the Democrats — and the South has become the national base of the GOP. In 1960, not one senator from one of the 11 Deep South states was a Republican. Today, a majority, 15, of them are.

A debate still rages over whether Kennedy would have tried to extract U.S. forces from Vietnam if he hadn't been assassinated.

Eisenhower sent the first U.S. military advisers to Vietnam, and 900 were on duty when he left office. During his presidency, Kennedy increased that deployment to more than 16,000. After taking over the White House, Johnson dramatically expanded the U.S. commitment: In 1968, there were more than half a million American troops there.

"He had been urged to go much further than Eisenhower, but Kennedy didn't do it, and I don't think he would have done so," Sorensen says, citing JFK's skeptical view of generals' advice in the wake of the disastrous Bay of Pigs invasion in 1961.

"In my view, evidence he would have pulled the plug is simply not persuasive," he says. He notes that Johnson was listening to the same aides who had surrounded Kennedy, among them Defense Secretary Robert McNamara and national security adviser McGeorge Bundy.

"When Kennedy came in, in 1961, he brought with him a variety of advisers who were committed to the proposition that armed force could be made politically useful even in a nuclear age," says Bacevich, author of Washington Rules: America's Path to Permanent War. "Vietnam provided the principle testing ground for that idea."

In his inaugural address, Kennedy famously pledged that the United States would "pay any price, bear any burden, meet any hardship" on behalf of liberty.

"I can remember being thrilled by that," says Lee Hamilton, elected to the House from Indiana the year after Kennedy's death and now president of the Woodrow Wilson International Center for Scholars. But in the wake of wars in Vietnam, Iraq and Afghanistan, he says: "It's baloney. Nobody believes that any more."

Kennedy's decision to increase rather than curtail the U.S. deployment in Vietnam left the door open for Johnson's enormous expansion, and all the consequences that followed. More than 58,000 Americans died in Vietnam, and the political debate over its course provoked demonstrations on college campuses and fueled a generation of cynicism toward the government.

Americans' wariness of long wars in distant places continues today, and Bacevich sees echoes of the Kennedy administration's doctrine toward Vietnam in the U.S.-led invasions of Iraq and Afghanistan.

"The promises of easy victory by superior U.S. forces have translated into very long, very dirty and costly wars," he says.

A modern presidency

Almost every Democratic presidential hopeful since Kennedy has tried to evoke his memory and manner.

A campaign ad for Bill Clinton in 1992 featured fuzzy footage of him as a student at Boys State, shaking hands with Kennedy at a Rose Garden event. John Kerry, another Massachusetts senator who won the Democratic presidential nomination, encouraged comparisons between him and JFK. Barack Obama's prospects in 2008 were boosted when he won the endorsement of Kennedy's daughter, Caroline Kennedy, and his brother, Sen. Edward Kennedy.

"I was Clinton's speechwriter, and we all thought the Kennedy precedent was extremely important," Widmer says, noting JFK's memorable language, his inclusive message to those who had been on the margins of politics and the energetic response he won from young people.

No modern president has so many widely remembered quotations, starting with his inaugural challenge to "ask not what your country can do for you."

When Wendy Kopp was researching the idea of a national teaching corps for her undergraduate thesis at Princeton — that paper laid the groundwork for the national organization called Teach for America— she researched the founding of the Peace Corps and even based the initial number of volunteers on the 500 that Peace Corps planners had concluded was ideal.

"I can't imagine that I would have thought of Teach for America without the Peace Corps" as a model and inspiration, she says. "His call to service is absolutely alive and well." Her organization, founded in 1990, fields 8,200 teachers in 31 states and the District of Columbia.

In the USA TODAY/Gallup Poll on Kennedy, taken Sept. 13-14, there is little difference by age in assessments of his presidency. Among seniors 65 and older, who presumably remember the time of his presidency, 29% say history will judge him as a great president. Among those 18 to 29 years old, who have only read about JFK and seen him in old TV clips, 30% do.

The survey of 1,014 adults has a margin of error of +/–4 percentage points.

Kennedy was the first and so far only Catholic elected president, a significant barrier at the time and one that has invited comparisons to Obama's election as the first African-American president.

He was also the first president comfortable in a new TV age. As a candidate, he and Republican nominee Richard Nixon held the first televised presidential debates. The first of the four was held on Sept. 26, 1960. And as president, he held the first live televised news conferences.

Before the election, Vanocur says, Kennedy had some reluctance about embracing TV, seeing Hugh Sidey of Time magazine and Ben Bradlee of Newsweek as more critical journalists to cultivate.

"I was at a party in Chicago as the Midwest correspondent for NBC at Sarge Shriver's house," Vanocur says. Kennedy's father, former ambassador Joseph Kennedy, was at the party hosted by Shriver, his son-in-law. "The ambassador came up and introduced himself to me, and said, 'I keep telling Jack, you are the guys who are the future.' But Kennedy was reluctant to accept that."

Eventually, JFK did, and a more personal style of politics emerged. He invited journalists to chronicle him sailing off the coast of Massachusetts and playing touch football with his extended family.

"Television has an awful lot to do with the Kennedy mystique and the fact that he's frozen in people's minds at the age of 46, and he was handsome and personable and witty and charming," says Robert Dallek, a presidential historian and author of An Unfinished Life: John F. Kennedy.

Disclosures about Kennedy's philandering and his efforts to hide serious health problems didn't emerge until years after his death.

Those belated disclosures tarnished his image and fueled a debate over the role of journalists who didn't report on them at the time of his presidency.

"There are some negatives, and one was the reckless personal behavior," including affairs with women who had links to Mob bosses and foreign intelligence agencies, says historian Alvin Felzenberg, who nonetheless put Kennedy among the top 10 in a book rating presidents. "I'm not talking morality; I'm talking about whether a president should be doing that."

Some historians say romantic views of JFK have led his influence to be overstated.

"Glamour overshadowed quality," Herbert Parmet concluded in his 1983 book, JFK: The Presidency of John F. Kennedy. "At best he was an 'interim' President who had promised but not performed."

But Kennedy's reputation has been burnished by comparison with the troubled presidencies that would follow: LBJ's entanglement in Vietnam, Nixon's resignation amid scandal, Clinton's impeachment and more. Like Ronald Reagan, Kennedy is remembered for a confident mien and buoyant message.

"For style and for creating a mood of optimism and hope — Kennedy on that count is as effective as any president the country has had in its history," Dallek says. "The question for me is, 100 years from now, will he be remembered? ...

"At the moment, he does have this astonishing hold on the public mind."

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